This application relates to wireless systems.
A wireless system refers to two or more user devices that communicate with each other without wires; instead the devices communicate using radio waves. The user devices may be personal computers, laptop computers, personal digital assistant (PDA), or the like. One example of a wireless system is a Local Area Network (LAN) that operates in a limited area, such as a home or business. A wireless LAN may also include a router or gateway device. The router or gateway device forwards data packets from a source to a destination. The router or gateway device may also be connected to a Wide Area Network (WAN), such as the Internet. For example, the router or gateway device may forward data received from the Internet to a particular user device on the LAN.
Transmissions between wireless devices generally use RF (Radio Frequency) signals. Each user device on the wireless LAN will typically include a transmitter and a receiver circuit, and one or more antenna elements for sending and receiving wireless signals. In some cases the transmitter and receiver circuit may be implemented in the same device, and referred to as a transceiver.
Wireless signals may become attenuated (e.g., lose signal strength) during transmission as the signal travels through walls or over long distances. Received RF signals may also include some amount of noise. The noise may reduce the accuracy of the system by causing errors in the received signal. The accuracy of a wireless system is generally evaluated by a Signal-to-Noise power Ratio (SNR) associated with a signal. The higher the SNR, the greater the accuracy. There are several different factors which may affect the SNR of a signal. For example, as a transmitter is moved farther away from a receiver, the received signal strength may be reduced and the SNR may be reduced. Therefore the noise in a received signal becomes more significant as the receiver is moved farther away from the transmitter. As another example, obstructions in the path between the transmitter and receiver may also lower the SNR. Along with this lessening of signal strength, other devices such as a Microwave oven or a cordless phone that radiate in the same spectrum cause interference with the signal.
Current products in the market typically use one antenna or sometime two antennae in the receiving circuit of a user device. If multiple antennae are used, only one antenna with the best signal to noise ratio is picked. They do not combine the antennae signals to increase the signal to noise ratio thus, not using the other antennae in the device efficiently.